Genentech is buying Seragon Pharmaceuticals Inc. for $725 million in cash, adding a treatment for breast cancer.

Seragon, headquartered in San Diego, is a biotechnology development company that is in Phase I trials for a product called ARN-810, which is being evaluated to treat metastic breast cancer. The group is also working on therapies for endometrial and ovarian cancers. The deal could be valued at up to $1.75 billion, including $1 billion of contingent development milestone payments.

Genentech, a member of the Roche Group (SIX: RO, ROG), is a biotechnology company that discovers, develops, manufactures and commercializes medicines to treat patients with serious or life-threatening medical conditions.

Companies developing innovative cancer treatments have been attractive targets for other drug companies. Recent deals include Celsion Corp.'s (Nasdaq: CLSN) purchase of Egen Inc. for $14 million in June, and the merger of Senesco Technologies Inc. and Fabrus Inc.